1. Field of the Invention
The subject invention relates to methods and apparatus for heating fluids and storing hot fluids and, more specifically, to methods and apparatus for heating fluids and storing hot fluids with the aid of vaporization and condensation of a heat transfer medium. By way of example, the subject invention relates to a water heater employing vaporization and condensation for heat transfer into a heat insulated storage tank of water.
2. Description of the Prior Art
By way of example, and not by way of limitation, it may be observed that the underlying concept of domestic water heating for all practical purposes has followed very much the same pattern for a century up to the present time. It is thus relatively easy to recognize the archetype of which the currently predominantly used water heater is a manifestation in such proposals as are apparent from U.S. Pat. No. 765,652, by P. A. Deasy, issued July 19, 1904, U.S. Pat. No. Re. 12,397, by P. A. Deasy, reissued Nov. 7, 1905, U.S. Pat. No. 1,719,015, by C. U. Levis, issued July 2, 1929, U.S. Pat. No. Re. 19,363, by O. W. Ott et al, issued Nov. 6, 1934, U.S. Pat. No. 2,322,488, by O. E. Uecker, issued June 22, 1943, U.S. Pat. No. 3,089,466, by W. W. Binger et al, issued May 14, 1963, U.S. Pat. No. 3,251,346, by A. Merino, issued May 17, 1966, and U.S. Pat. No. 3,707,142, by Shiro Kobayashi, issued Dec. 26, 1972. Interestingly, the above mentioned Deasy patents provided the water heater with a facility for supplying the water-back of a stove with hot water. This is somewhat related to the proposal in U.S. Pat. No. 765,651, by P. A. Deasy, issued also on July 19, 1904, according to which the actual heating of the water takes place outside the hot water storage tank.
The proposals in U.S. Pat. No. 1,822,871, by J. P. Morley, issued Sept. 8, 1931, constitute a mixture of the archetypal, presently most widely used water heater and of the type of heater wherein the heating takes place separately from the hot water storage tank. Reference may in this connection also be had to U.S. Pat. No. 189,421, by Joshua Bishop, issued Apr. 10, 1877, U.S. Pat. No. 1,830,933, by Alfred F. Coony, issued Nov. 10, 1931, U.S. Pat. No. 2,399,318, by J. W. Bouldin, issued Apr. 30, 1946, U.S. Pat. No. 2,563,817, by H. J. Carson, issued Aug. 14, 1951, U.S. Pat. No. 2,650,575, by A. W. Carlson, issued Sept. 1, 1953, and U.S. Pat. No. 2,684,054, by H. J. Carson, issued July 20, 1954.
These prior-art heaters are characterized by high losses and inefficiency, and the currently most widely used gas water heater has aggravated, rather than alleviated, the problem by its use of a central riser or chimney for the hot products or combustion. In principle, such central riser through the water tank enables the products of combustion of the heating process to help heating the water. However, in overall effect such a riser is detrimental since it provides an escape path for heat from the hot water in the tank during the long intervals between heating cycles.
In the case of designs wherein the heating of the water takes place at a distance from the tank, similar heat losses occur as to the water present in the heater part of the installation. Further heat losses are added when hot water is circulated, by convection, to the cooled heater and then back into the storage water tank. This action follows rather closely the detrimental cooling encountered in the above mentioned central riser type of water heater.
In power plants, ships and other special installations, steam has sometimes been used in heating water. For instance, steam has simply been issued into the water for heating purposes. In practice, this is a very wasteful process that would not be feasible for most typical water heating purposes. Alternatively, steam and condensate have been circulated through a closed system. Again, existing systems are rather wasteful and not usable in typical water heater environments.